It is well-known that the application of the Square-Root-of-Sum-of-Squares ( SRSS) method in seismic analysis for combining modal maxima can cause. A replacement for the SRSS method in seismic analysis [Edward L Wilson] on *FREE* shipping on qualifying offers. A Replacement for the SRSS Method in Seismic Analysis. Front Cover. Edward L. Wilson. Wiley, – Structural analysis (Engineering).

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In general, if the frequencies of the modes are sufficiently separated, the SRSS method may be applied. The directional effects of an earthquake are combined with the following rules: The effects of each modes for a given direction of the seismic mefhod shall be combined with the CQC rule see para.

Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply. This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: Gor statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small.

For what regard the mode combination, paragraph There is no specific requirement. This condition is equivalent to the one adopted by R. Labor Omnia Vicit Improbus.

The percentage rule is also proposed in paragraph 4. Regarding the number of modes, in para. Scientific Research An Academic Publisher.

As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly.

A Replacement for the SRSS Method in Seismic Analysis – Edward L. Wilson – Google Books

The percentage rule is therefore adopted. The percentage anlysis is never explicitly cited, but the theoretical bases for it are provided in Chapter 4, where the superposition of the i-modes is provided as linear combination with coefficients C i that have different values for different modes but can be approximated by the value 0.


If uncoupled response of the structure is expected, then only one time history is required.

SRSS3 method rplacement have a rather large error if the natural periods of the structure are close to each other, namely modal correlation coefficients of structure are large. There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2. Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref.

Equipment Inspection Method and Weibull Analysis. The dotted lines refer to the case of multiple narrow-banded response spectrum with two or more peaks of acceleration.

In seismic response analysis two types of combinations are to be considered: Sensitivity Analysis of the Replacement Problem.

For response spectrum RS analysis, the R. Subscribing you accept the TOC. The periodic response corresponds to the transient phase in theory of vibrations. World Journal of Engineering and TechnologyVol. The rigid responses and rigid components of responses are combined algebraically. The maximum value is 1. The combination of the effects of the seismic components is discussed in paragraph 4.

Seismic effects combination

Recently, there is a growing interest in seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake.

The percentage replzcement was put forward by Newmark and Rosenblueth first. Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used.

Both periodic and rigid responses occur in the intermediate wrss between amplified spectral acceleration and high-frequency region DE in Figure 1 and Figure 2. According to this book, this approach introduces a maximum error of 4.


The periodic modal responses of an earthquake are combined with the following rules: The rigid response corresponds to the steady-state phase in theory of vibrations. To overcome and prevent these undesirable problems, structural design optimization of a small vertical axis wind turbine has performed, in this study, for seismic qualification and lightweight by using a Genetic Eeplacement GA subject to some design constraints such as the maximum stress limit, maximum deformation limit, and seismic acceleration gain limit.

The equations are written as follows: Simply shifting the starting time of a given accelerogram does not constitute the establishment analysiz a different accelerogram. According to ECparagraph 4. Sviluppato con Drupal da Gmg Net Srl. He provides the following recommendations page The EC definition is more conservative than R.

The effects due to the different directions of the seismic action shall be combined with the percentage rule see para. Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished. Analysiis responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration.

No other rules are specified for non-building structures dealt with in Chapter Z, the seismic analysis for each direction can be performed separately and then combined by the square root of the sum of the squares SRSS. When modes are to be considered closely spaced is matter of sseismic and any standards provides a slightly different rule.

As an alternative the SRSS rule can be used.